Methodology

Victimization is the basic unit of analysis used throughout this
tool. A victimization refers to a single victim or household that
experienced a crime. Crimes are distinguished from victimizations in
that one crime may have multiple victims.

For violent crimes (rape or sexual assault, robbery, aggravated
assault, and simple assault) and for personal larceny, the count of
victimizations is the number of individuals who experienced a crime.
For crimes against households (burglary, theft, and motor vehicle
theft), each household affected by a crime is counted as a single
victimization.

For violent victimizations, the victim, household, and incident
characteristics included in this analysis tool are—

victim's sex

victim's age

victim's race

victim's Hispanic origin

victim's race/Hispanic origin

victim's marital status

household income

victim-offender relationship

presence of weapon

weapon category

reporting to the police

urbanicity

region

population size

injury

medical treatment for physical injuries

victim services

location of incident

location of residence

marital status

type of crime

aggregate type of crime

serious violent victimization.

For property victimizations, the household characteristics
included in the analysis tool are—

head of household's sex

head of household's age

head of household's race

head of household's race/Hispanic origin

household income

household size

reporting to the police

urbanicity

region

population size

victim services

location of incident

location of residence

aggregate type of crime

type of crime.

Estimates from the tool may differ from estimates in previous BJS publications that use NCVS data. This is because a few victimizations, referred to as series victimizations, are included in the analysis tool using a different counting strategy. High-frequency repeat victimizations, or series victimizations, are six or more similar but separate victimizations that occur with such frequency the victim is unable to recall each individual event or describe each event in detail. BJS counts series victimizations using the victim's estimate of the number of times the victimizations occurred during the prior 6 months, capping the number within each series at a maximum of 10 victimizations. Including series victimizations in national estimates can substantially increase the number and rate of violent victimization. However, trends in violent crime are generally similar regardless of whether series victimizations are included. Additional information on the series enumeration is detailed in the report
Methods for Counting High-Frequency Repeat Victimizations in the National Crime Victimization Survey.

Data collection

The NCVS is an annual data collection conducted by the U.S. Census Bureau for BJS. The NCVS collects information on nonfatal victimizations, reported and not reported to the police, against persons age 12 or older from a nationally representative sample of U.S. households.

The estimates presented in the tool are based on data gathered
from residents living throughout the United States, including persons
living in group quarters, such as dormitories, rooming houses, and
religious group dwellings. Armed Forces personnel living in military
barracks and institutionalized persons, such as correctional facility
inmates, are not included in the scope of this survey.

Each housing unit selected for the NCVS remains in the sample for 3 years, with each of 7 interviews taking place at 6-month intervals. An NCVS field representative's first interview with a household selected for the survey is conducted in person. The majority of follow-up interviews are conducted by telephone.

Collection and reporting of race and ethnicity data

In 1997, the Office of Management and Budget (OMB) introduced new guidelines for the collection and reporting of race and ethnicity data in government surveys. BJS implemented these methodological changes for all demographic surveys on January 1, 2003. In prior years, respondents were asked to select a single primary race. BJS now allows individuals to choose more than one racial category. BJS asks individuals whether they are of Hispanic ethnicity before asking about their race and asks people directly if they are Spanish, Hispanic, or Latino.

Accuracy of estimates

The accuracy of an estimate is a measure of its total error, that is, the sum of all the errors affecting the estimate. This includes sampling error and nonsampling error.

BJS selects a sample from the entire population to use for the
NCVS. BJS could have chosen from a large number of other possible
samples of equal size that could have been obtained by using the same
sample design and selection procedures. The estimates derived from any
one of these samples would differ from one another due to sampling
variability or sampling error. Sampling error is often quantified
with the standard error as described below.

In addition to sampling error, the estimates in this analysis tool are subject to nonsampling error. Sources of nonsampling error include nonresponse error, respondent recall error, poorly worded questions, interviewer and mode effects on response, and data entry error. While substantial care is taken in the NCVS to reduce the sources of nonsampling error throughout all of the survey operations by means of a quality assurance program, quality controls, operational controls, and error-correcting procedures, an unquantified amount of nonsampling error remains. These nonsampling errors are difficult to measure.

Decennial Sample Redesign

In 2006 and 2016, the NCVS sample was redesigned to reflect changes in the population based on the most recent Decennial Census. The redesign impacted the comparability of 2006 and 2016 estimates to prior years of data. Use caution when comparing 2006 and 2016 estimates to other years. See Criminal Victimization, 2006 Technical Notes (BJS Web, NCJ 219413, December 2007), Criminal Victimization, 2007 (BJS Web, NCJ 224390, December 2008) and Criminal Victimization, 2016 (BJS Web, NCJ 250652, November 2017) for more information.